Re: [PATCH v5 00/12] MADV_FREE support

[Michael Kerrisk (man-pages)]

Hello Minchan,

On 11/30/2015 07:39 AM, Minchan Kim wrote:
> In v4, Andrew wanted to settle in old basic MADV_FREE and introduces
> new stuffs(ie, lazyfree LRU, swapless support and lazyfreeness) later
> so this version doesn't include them.
> 
> I have been tested it on mmotm-2015-11-25-17-08 with additional
> patch[1] from Kirill to prevent BUG_ON which he didn't send to
> linux-mm yet as formal patch. With it, I couldn't find any
> problem so far.
> 
> Note that this version is based on THP refcount redesign so
> I needed some modification on MADV_FREE because split_huge_pmd
> doesn't split a THP page any more and pmd_trans_huge(pmd) is not
> enough to guarantee the page is not THP page.
> As well, for MAVD_FREE lazy-split, THP split should respect
> pmd's dirtiness rather than marking ptes of all subpages dirty
> unconditionally. Please, review last patch in this patchset.

Now that MADV_FREE has been merged, would you be willing to write
patch to the madvise(2) man page that describes the semantics, 
noes limitations and restrictions, and (ideally) has some sentences
describing use cases?

Thanks,

Michael


> 	mm: don't split THP page when syscall is called
> 
> [1] https://lkml.org/lkml/2015/11/17/134
> 
> git: git://git.kernel.org/pub/scm/linux/kernel/git/minchan/linux.git
> branch: mm/madv_free-v4.4-rc2-mmotm-2015-11-25-17-08-v5r2
> 
> In this stage, I don't think we need to write man page.
> It could be done after solid policy and implementation.
> 
>  * Change from v4
>    * drop lazyfree LRU
>    * drop swapless support
>    * drop lazyfreeness
>    * rebase on recent mmotom with THP refcount redesign
> 
>  * Change from v3
>    * some bug fix
>    * code refactoring
>    * lazyfree reclaim logic change
>    * reordering patch
> 
>  * Change from v2
>    * vm_lazyfreeness tuning knob
>    * add new LRU list - Johannes, Shaohua
>    * support swapless - Johannes
> 
>  * Change from v1
>    * Don't do unnecessary TLB flush - Shaohua
>    * Added Acked-by - Hugh, Michal
>    * Merge deactivate_page and deactivate_file_page
>    * Add pmd_dirty/pmd_mkclean patches for several arches
>    * Add lazy THP split patch
>    * Drop zhangyanfei@xxxxxxxxxxxxxx - Delivery Failure
> 
> Chen Gang (1):
>   arch: uapi: asm: mman.h: Let MADV_FREE have same value for all
>     architectures
> 
> Minchan Kim (11):
>   mm: support madvise(MADV_FREE)
>   mm: define MADV_FREE for some arches
>   mm: free swp_entry in madvise_free
>   mm: move lazily freed pages to inactive list
>   mm: mark stable page dirty in KSM
>   x86: add pmd_[dirty|mkclean] for THP
>   sparc: add pmd_[dirty|mkclean] for THP
>   powerpc: add pmd_[dirty|mkclean] for THP
>   arm: add pmd_mkclean for THP
>   arm64: add pmd_mkclean for THP
>   mm: don't split THP page when syscall is called
> 
>  arch/alpha/include/uapi/asm/mman.h       |   2 +
>  arch/arm/include/asm/pgtable-3level.h    |   1 +
>  arch/arm64/include/asm/pgtable.h         |   1 +
>  arch/mips/include/uapi/asm/mman.h        |   2 +
>  arch/parisc/include/uapi/asm/mman.h      |   2 +
>  arch/powerpc/include/asm/pgtable-ppc64.h |   2 +
>  arch/sparc/include/asm/pgtable_64.h      |   9 ++
>  arch/x86/include/asm/pgtable.h           |   5 +
>  arch/xtensa/include/uapi/asm/mman.h      |   2 +
>  include/linux/huge_mm.h                  |   3 +
>  include/linux/rmap.h                     |   1 +
>  include/linux/swap.h                     |   1 +
>  include/linux/vm_event_item.h            |   1 +
>  include/uapi/asm-generic/mman-common.h   |   1 +
>  mm/huge_memory.c                         |  87 +++++++++++++-
>  mm/ksm.c                                 |   6 +
>  mm/madvise.c                             | 199 +++++++++++++++++++++++++++++++
>  mm/rmap.c                                |   8 ++
>  mm/swap.c                                |  44 +++++++
>  mm/swap_state.c                          |   5 +-
>  mm/vmscan.c                              |  10 +-
>  mm/vmstat.c                              |   1 +
>  22 files changed, 383 insertions(+), 10 deletions(-)
> 


-- 
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/